Mo修饰的钼铁复合催化剂及其煤直接液化催化性能

Mo modified Mo-Fe composite catalysts and their catalytic performance in direct coal liquefaction

分别在Fe催化剂制备的沉淀、氧化和干燥阶段引入Mo合成了五种Mo修饰的钼铁复合催化剂,调控了Mo和Fe的结合形式。利用XRD、SEM、TEM、BET、XRF、XPS和H_(2)-TPR对催化剂进行表征,在500 ml高压釜内进行神华上湾煤的直接液化实验。结果表明,钼铁协同催化作用促进了氢的活化和煤的分解,Mo修饰的复合催化剂的煤直接液化活性明显提高。Mo在催化剂表层分布有利于活性氢在工业循环溶剂和沥青类物质中的传递,促进沥青转化为油。Mo与Fe共沉淀会影响铁氧化物晶体形成和生长,使晶粒尺寸下降,比表面积和可还原度升高。Mo从氨水中引入形成均匀分散的小晶粒Mo-Fe复合化合物,液化油产率提高4.4%。浸渍引入Mo不改变铁氧化物结构,但Mo富集于催化剂表面提高了与反应物的碰撞概率,液化油产率提高5.0%。

Five kinds of Mo modified Mo-Fe composite catalysts were synthesized by introducing Mo into the precipitation,oxidation and drying stages of Fe catalyst preparation,by which the binding forms of Mo and Fe could be regulated.The catalysts were characterized by XRD,SEM,TEM,BET,XRF,XPS and H_(2)-TPR.The Shenhua Shangwan coal hydroliquefaction experiment was carried out in a 500 ml autoclave.The results show that the synergistic effect of Mo and Fe promoted the activation of hydrogen and the decomposition of coal,and the activities of Mo modified composite catalysts for direct coal liquefaction were significantly improved.The high distribution of Mo on the surface is beneficial to the transfer of active hydrogen from solvents to asphaltenes,and promotes the conversion of asphalt into oil.Mo co-precipitation with Fe affected the crystal growth of iron-oxygen compounds,with the decrease of the grain size,and the increase of the specific surface area and reducibility.Mo-Fe compound synthesis by introducing Mo into ammonia solution,with uniform distribution of Mo,showed high catalytic activity and the yield of liquefaction oil increased by 4.4%.The impregnation of Mo into Fe-based catalyst did not change the structure of iron-oxygen compound,but the enrichment of Mo on the catalyst surface increased the collision probability with reactants,and the yield of liquefaction oil increased by 5.0%.